1. Field of the Invention
The present invention relates to an improvement in the vibration absorber used for mounting a power unit (the engine and transmission together) in an automotive vehicle, and more specifically to the shapes of the rubber members used for the vibration absorber such that multistep vibration absorbing characteristics are provided, depending upon the shear and compression rates of deformation of the rubber member.
2. Description of the Prior Art
In order to absorb the vibration generated by the power unit of an automotive vehicle, there exist various vibration absorbers. In these prior-art vibration absorbers, usually two-step nonlinear vibration absorbing characteristics are required in order that the vibration is effectively damped by the shear deformation of the vibration absorbing rubber member when the vibration is relatively small and by the compression deformation thereof when the vibration is great. In this case however, since the vibration absorbing characteristics change abruptly, a sudden, unpleasant shock can be applied to the passengers.
Additionally, when the vehicle is gradually accelerated or decelerated, a certain amount of load is applied to the vibration absorber, and therefore small vibrations are transmitted to the vehicle body, since the rubber member is left deformed within the compression region beyond the shear region, thus resulting in a phenomenon called shuddering because the elasticity in the compression region is relatively great compared with that in the shear region.
A more detailed description of prior-art vibration absorbers will be made hereinafter with reference to FIG. 1 and FIG. 2.